Credit Quality of Loans and Allowance for Loan Losses - Loan Portfolio and Concentrations (Details) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($) industry_concentration	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Loan portfolio [Abstract]
Loans	$ 1,272,800	$ 1,263,645	$ 1,301,452
Less allowance for loan losses	(23,268)	(19,011)
Loans, net	$ 1,249,532	1,244,634
Number of industry segment concentration above threshold limit \| industry_concentration	1
Concentration risk, percentage	10.00%
Loans exposure in oil and gas industry	$ 243,300
Exposure in the oil and gas industry specified as percentage of total loans	19.10%
Loans with exposure in commercial real estate	$ 542,200
Loans on nonaccrual status	60,522	50,051
Commercial, financial and agricultural
Loan portfolio [Abstract]
Loans	463,031	454,028	482,452
Loans on nonaccrual status	29,874	27,705
Real estate - construction
Loan portfolio [Abstract]
Loans	96,365	74,952	74,279
Loans on nonaccrual status	10	37
Real estate – commercial
Loan portfolio [Abstract]
Loans	$ 464,853	471,141	473,319
Percentage of CRE loans secured by owner-occupied commercial properties	54.00%
Loans on nonaccrual status	$ 28,285	19,907
Nonaccrual status of loans specified as percentage of total CRE loans	5.20%
Real estate – residential
Loan portfolio [Abstract]
Loans	$ 155,653	149,064	151,667
Loans on nonaccrual status	1,889	1,998
Installment loans to individuals
Loan portfolio [Abstract]
Loans	88,537	111,009	113,199
Loans on nonaccrual status	464	404
Lease financing receivable
Loan portfolio [Abstract]
Loans	1,449	1,968	4,790
Loans on nonaccrual status	0	0
Other
Loan portfolio [Abstract]
Loans	2,912	1,483	$ 1,746
Loans on nonaccrual status	$ 0	$ 0

This line item represents the exposure in the oil and gas industry specified as a percentage of total loans.

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This line item represents the loans exposure in the oil and gas industry.

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This line item represents the loans with exposure in the commercial real estate section.

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This line item represents the percentage of nonaccrual status of loans specified as percentage of total CRE loans.

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This line item represents the number of industry segment concentration above threshold limit of the loan portfolio.

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This line item represents the percentage of CRE loans secured by owner occupied commercial properties.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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